• International Journal of Control, Automation, and Systems
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• 제6권4호
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• pp.620-625
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• 2008

The $H_{\infty}$ entropy in $H_{\infty}$ control theory is discussed based on investigating information transmission in continuous-time linear stochastic systems. It is proved that the stabilizing feedback does not change the time-average information transmission between system input and output, and the $H_{\infty}$ entropies of open- and closed-loop stable transfer functions are bounded by mutual information rate between input and output in the open-loop system. Furthermore, a new $H_2$ upper bound for $H_{\infty}$ entropy is introduced with a numerical example. Thus the $H_{\infty}$ entropy of a stable transfer function is sandwiched between $H_2$ norms of the original system and a static feedback system.

• 전력전자학회논문지
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• 제4권1호
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• pp.43-49
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• 1999

본 연구에서는 비선형 시스템을 선형 시스템으로 변환시키는 미분기하이론에 기초를 둔 비선형 궤환 선형화 기법을 유도전동기와 같은 비선형 시스템의 제어에 응용함으로써 완전한 비간섭 시스템을 얻을수 있음을 보였다. 또한, 엘리베이터와 같은 부하의 정속도 운전시 효율제어를 위해 회전자 자속을 변화시킬 때 이의 영향을 받아 값이 바뀌는 인덕턴스와 온도에 따라 가장 변화가 심한 회전자저항을 위한 추정알고리즘을 제안하고 이의 성능을 평가해 보기 위하여 시뮬레이션과 실험을 수행하였다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1996년도 한국자동제어학술회의논문집(국내학술편); 포항공과대학교, 포항; 24-26 Oct. 1996
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• pp.1253-1256
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• 1996

In this paper, a new nonlinear feedback linearization control scheme for induction motors is developed. The control scheme employs a fuzzy nonlinear identification scheme based on fuzzy basis function expansion to adoptively compensate the parameter variations, i.e. rotor resistance, mutual and self inductance etc. An important feature of the proposed control scheme is to incorporate the sliding mode controller into the scheme to speed up convergence rate. Simulation tests show the robust behavior of the proposed controller in the presence of the parameter uncertainties of the machine.

• 공학교육연구
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• 제25권5호
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• pp.94-103
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• 2022

In this study, we examined the cases of online video classes conducted under the COVID-19 situation for 46 first-year students majoring in electrical engineering at a 3-year college in Gyeongnam. The research was carried out according to the course development process so that classes could be conducted efficiently, focusing on electromagnetism(1) course in the second semester of the first year. The online class consisted of uploading PPT recorded videos and lecture materials to the LMS and giving assignments. The contents of the study were in the scope of examining learners' perceptions through online learning contents, assignment submission, mutual feedback between instructors and learners, university-level lecture evaluation, and free opinions on online video-based electromagnetism(1) classes. As a result of the study, it was confirmed that online lecture review and problem-solving are particularly important for understanding lecture materials, and also given the nature of engineering subjects that require plenty of mathematical expressions, the detailed and immediate feedback provided by instructor enhances learners' class satisfaction and understanding. Based on these, the direction of online classes to be developed after the COVID-19 pandemic and teaching and learning methods suitable for the characteristics of subjects were discussed.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1998년도 전력전자학술대회 논문집
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• pp.239-244
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• 1998

We propose a nonlinear feedback controller that can control the induction motors with high dynamic performance by means of decoupling of motor speed and rotor flux. A new recursive adaptation algorithm for rotor resistance which can be applied to our nonlinear feedback controller is also presented in this paper. Some simulation results show that the adaptation algorithm for rotor resistance is robust against the variation of stator resistance and mutual inductance. In addition, it is computationally simple and has small estimation errors.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1998년도 Proceedings ICPE 98 1998 International Conference on Power Electronics
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• pp.23-28
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• 1998

We propose a nonlinear feedback controller that can control the induction motors with high dynamic performance by means of decoupling of motor speed and rotor flux. The nonlinear feedback controller needs the information on some motor parameters. Among them, rotor resistance varies greatly with machine temperature. A new recursive adaptation algorithm for rotor resistance which can be applied to our nonlinear feedback controller is also presented in this paper. The recursive adaptation algorithm makes the estimated value of rotor resistance track its real value. Some simulation results show that the adaptation algorithm for rotor resistance is robust against the variation of stator resistance and mutual inductance. In addition, it is computationally simple and has small estimation errors. To demonstrate the practical significance of our results, we present some experimental results.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.139.4-139
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• 2001

The thesis propose the sensorless vector control method that estimates the rotor speed using stator current. The estimated speed is used as feedback in a vector control system. The conventional MRAS structure has a problem the error output is decreasing as estimated speed error is increasing and the estimation performance is not robust when mutual inductance has been changed. In the proposed method, error output is proportional to estimated speed error. The described technique is less complex, robust to variations of mutual inductance. This new method can achieve much wider bandwidth speed control than that of the conventional MRAS structure.

• 융합보안논문지
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• 제14권6_2호
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• pp.63-72
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• 2014

이 연구는 경찰공무원의 조직문화와 직무특성 및 직무지속의지를 규명하는데 있다. 이 연구는 2012년 수도권소재(서울) 경찰공무원들을 연구대상으로 선정한 후 판단표집법(judgment sampling method)을 이용하여 최종분석에 이용된 사례 수는 총 187명이다. 분석방법은 SPSSWIN 18.0을 이용하여 빈도분석, 요인분석, 신뢰도분석, 다중회귀분석 등을 실시하였다. 결론은 다음과 같다. 첫째, 경찰공무원의 조직문화는 직무특성에 영향을 미친다. 즉, 개발합의적 문화, 위계적 문화가 형성될수록 피드백은 증대되며, 위계적 문화, 합리적 문화가 형성될수록 직무중요성은 높다. 또한, 개발합의적 문화가 형성될수록 자율성은 높다. 둘째, 경찰공무원들의 조직문화는 직무지속의지에 영향을 미친다. 즉, 개발합의적 문화가 형성되면 직무기대만족은 증대 되는 반면 고의적불성실은 감소한다. 또한 위계적 문화가 형성될수록 위기지각 행동은 증가한다. 셋째, 경찰공무원의 직무특성은 직무지속의지에 영향을 미친다. 즉, 피드백과 직무중요성이 부각되면 직무기대만족은 증대되는 반면, 기능다양성은 감소한다. 또한 피드백 기능이 부각되면 위축요인을 감소한다. 직무중요성을 높게 인식할수록 고의적불성실을 증대되는 반면, 기능다양성은 감소한다. 기능다양성을 높게 인식할수록 대안기대는 증가하며, 직무중요성, 자율성, 기능다양성을 높게 인식할수록 위기지각은 증대된다.

• Journal of Mechanical Science and Technology
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• 제16권8호
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• pp.1039-1052
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• 2002

This paper presents an application where a Fuzzy-Logic Controller (FLC) is used at a supervisory level to implement mutual coordination of the steering of the two front wheels of a motorcar. The two front wheels are steered by two independent discrete time state feedback controllers with a view to optimize the steering slip angles. The functions of the two controllers are tied together by way of a FLC. Because of the presence of unmodelled dynamics and disturbances acting on the two sides, it is difficult to achieve the desired performance using conventional control systems. This is the primary reason that FLC is emploged to solve the problem. The results show that the implemented system achieved desired coupling between the two independent systems and thereby reduces the difference between the two steered angles.

• Journal of Advanced Marine Engineering and Technology
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• 제33권6호
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• pp.932-938
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• 2009

As a stringing troy wire is installed by manual operation, it is necessary to scheme the automatic system for stringing troy wire. To accomplish a task of this kind, in this paper an approach to designing controllers for the hybrid Position/Tension control of a stringing troy wire is presented. Position control system is designed based on equation of dc motor and motion equation of robot, it is controlled by feedback with a detected speed dc motor. Tension control system is designed based on equation of ac servomotor for generating torque and dynamic equation of a troy wire, it is controled by feedback with a detected tension. The control parameters is determined by simulation in independence operation of each system. To suppress a mutual interference that the disturbance occur in operating of two task at same time. Dynamic hybrid control is proposed by feed forward compensator with a disturbance accelerator and a step torque at start. The operation of proposed system is simulated and experimented, results is verified the utilities.